Response characteristics of soil–underground structures under horizontal pushover

The deformation of underground structures is restricted by that of the surrounding soil during earthquake. In order to reveal the complex interaction between the soil and the underground structures, based on the self-developed geotechnical comprehensive test model box, a large-scale pushover test on soil–underground structures is carried out with soil deformation as the control variable aiming at a single-story box type underground structure in sandy soil. The pushing plate in the model box is pushed horizontally according to the inverted triangle distribution displacement mode, namely the pushing plate is rotated around the bottom, and the rotation angle increases step by step from 0 to 1/60. The response characteristics of the underground structures and the surrounding soil under pushover action are mainly compared. The test results show that a horizontal penetration crack occurs at 6 cm above the middle of the inner wall in the pushing end when the rotation angle reaches 1/120, and a horizontal penetration crack occurs at 11 cm below the middle of the inner wall in the passive end when it reaches 1/150. The underground structures are subjected to the coupled action of extrusion deformation and shear deformation. The horizontal relative displacement between top and bottom of the side wall in the pushing end is significantly smaller than that of the soil at the corresponding position in auxiliary observation plane, and the deformation ratio of the structures to the soil increases from 0.44 to 0.75 after failure of the side wall. Meanwhile, the ratio of inverted triangle horizontal load between the soil and the structures decreases from 0.24 in the initial stage of the test to 0.10 and keeps stable, then increases to 0.32 after failure of the structures, and the degree of soil–structure interaction varies with the state change of the soil and structures. The horizontal coefficient of subgrade reaction in the soil decreases with the increase of loading level, and always changes within the given range of code. However, the horizontal coefficient of subgrade reaction on side wall fluctuates widely due to the failure of the structure and stress concentration at the corner.